1. Field of the Invention
The present invention relates to compounds of the formula I, ##STR2## in which B, E, W, Y, Z, R, R.sup.2, R.sup.2a, R.sup.2b, R.sup.3, g and h have the meanings indicated below. The compounds of the formula I are valuable pharmaceutical active compounds, which are suitable, for example, for the therapy and prophylaxis of inflammatory disorders, for example of rheumatoid arthritis, or of allergic disorders. Compounds of the formula I are inhibitors of the adhesion and migration of leukocytes and/or antagonists of the adhesion receptor VLA4 belonging to the integrin group of receptors. They are generally suitable for the therapy or prophylaxis of illnesses which are caused by an undesired extent of leukocyte adhesion and/or leukocyte migration or are associated therewith, or in which cell-cell or cell-matrix interactions which are based on interactions of VLA4 receptors with their ligands play a part. The invention furthermore relates to processes for the preparation of the compounds of the formula I, their use in the therapy and prophylaxis of the disease states mentioned, and to pharmaceutical preparations which contain the compounds of the formula I.
2. Description of Related Art
The integrins are a group of adhesion receptors which play an important part in cell-cell-binding and cell-extracellular matrix-binding processes. They have an .alpha..beta.-heterodimeric structure and exhibit a wide cellular distribution and are closely structurally related. The integrins include, for example, the fibrinogen receptor on platelets, which interacts especially with the RGD sequence of fibrinogen, or the vitronectin receptor on osteoclasts, which interacts especially with the RGD sequence of vitronectin or of osteopontin. The integrins are divided into three major groups; the .beta.2 subfamily with the representatives LFA-1, Mac-1 and p150/95, which are responsible in particular for cell-cell interactions of the immune system; and the subfamilies .beta.1 and .beta.3, whose representatives mainly mediate cell adhesion to components of the extracellular matrix (Ruoslahti, Annu. Rev. Biochem. 1988, 57, 375). The integrins of the .beta.1 subfamily, also called VLA proteins (very late (activation) antigen), include at least six receptors which interact specifically with fibronectin, collagen and/or laminin as ligands. Within the VLA family, the integrin VLA4 (.alpha.4.beta.1) is atypical, insofar as it is mainly restricted to lymphoid and myeloid cells and is responsible in these cells for cell-cell interactions with a large number of other cells. For example, VLA4 mediates the interaction of T and B lymphocytes with the heparin II-binding fragment of human plasma fibronectin (FN). The binding of VLA4 with the heparin II-binding fragment of plasma fibronectin is especially based on an interaction with an LDVP sequence. In contrast to the fibrinogen or vitronectin receptor, VLA-4 is not a typical RGD-binding integrin (Kilger and Holzmann, J. Mol. Meth. 1995, 73, 347).
The leucocytes circulating in the blood normally exhibit only a low affinity for the vascular endothelial cells which line the blood vessels. Cytokines which are released from inflamed tissue cause the activation of endothelial cells and thus the expression of a large number of cell surface antigens. These include, for example, the adhesion molecules ELAM-1 (endothelial cell adhesion molecule-1; also designated as E-selectin), which, inter alia, binds neutrophiles, ICAM-1 (intercellular adhesion molecule-1), which interacts with LFA-1 (leucocyte function-associated antigen 1) on leucocytes, and VCAM-1 (vascular cell adhesion molecule-1), which binds various leucocytes, inter alia lymphocytes (Osborn et al., Cell 1989, 59, 1203). VCAM-1, like ICAM-1, is a member of the immunoglobulin gene superfamily. VCAM-1 (first known as INCAM-110) was identified as an adhesion molecule which is induced on endothelial cells by inflammatory cytokines such as TNF and IL-1 and lipopolysaccharides (LPS). Elices et al. (Cell 1990, 60, 577) showed that VLA4 and VCAM-1 form a receptor-ligand pair which mediates the adhesion of lymphocytes to activated endothelium. The binding of VCAM-1 to VLA-4 does not occur via an interaction of the VLA-4 with an RGD sequence; VCAM-1 does not contain such a sequence (Bergelson et al., Current Biology 1995, 5, 615). VLA4, however, also occurs on other leucocytes, and the adhesion of leucocytes other than lymphocytes is also mediated via the VCAM-1/VLA4 adhesion mechanism. VLA4 thus represents an individual example of a .beta.1 integrin receptor which, via the ligands VCAM-1 and fibronectin, plays an important part both in cell-cell interactions and in cell-extracellular matrix interactions.
The cytokine-induced adhesion molecules play an important part in the recruitment of leucocytes into extravascular tissue regions. Leucocytes are recruited into inflammatory tissue regions by cell adhesion molecules which are expressed on the surface of endothelial cells and serve as ligands for leucocyte cell surface proteins or protein complexes (receptors) (the terms ligand and receptor are interchangeable in this context). Leucocytes from the blood first must adhere to endothelial cells before they can migrate into the synovium. Since VCAM-1 binds to cells which carry the integrin VLA-4 (.alpha.4.beta.1), such as eosinophils, T and B lymphocytes, monocytes or else neutrophils, it and the VCAM-1/VLA-4 mechanism have the function of recruiting cells of this type from the blood stream into areas of infection and inflammatory foci (Elices et al., Cell 1990, 60, 577; Osborn, Cell 1990, 62, 3; Issekutz et al., J. Exp. Med. 1996, 183, 2175).
The VCAM-1/VLA4 adhesion mechanism has been connected with a number of physiological and pathological processes. Apart from cytokine-induced endothelium, VCAM-1 is additionally expressed, inter alia, from the following cells: myoblasts, lymphoid dendritic cells and tissue macrophages, rheumatoid synovium, cytokine-stimulated neural cells, parietal epithelial cells of the Bowman's capsule, the renal tubular epithelium, inflamed tissue during heart and kidney transplant rejection and by intestinal tissue in graft-versus-host disease. VCAM-1 is also found to be expressed on those tissue areas of the arterial endothelium which correspond to early arteriosclerotic plaques of a rabbit model. Additionally, VCAM-1 is expressed on follicular dendritic cells of human lymph nodes and is found on stroma cells of the bone marrow, for example in the mouse. The latter finding points to a function of VCAM-1 in B-cell development. Apart from cells of hematopoietic origin, VLA4 is also found, for example, on melanoma cell lines, and the VCAM-1VLA-4 adhesion mechanism is connected with the metastasis of such tumors (Rice et al., Science 1989, 246, 1303).
The main form in which VCAM-1 occurs in vivo on endothelial cells, and which is the dominant form in vivo, is designated as VCAM-7D and contains seven immunoglobulin domains. The domains 4, 5 and 6 are similar in their amino acid sequences to the domains 1, 2 and 3. The fourth domain is removed in a further form, consisting of six domains, designated here as VCAM-6D, by alternative splicing. VCAM-6D can also bind VLA4-expressing cells.
Further details on VLA-4, VCAM-1, integrins and adhesion proteins are found, for example, in the articles by Kilger and Holzmann, J. Mol. Meth. 1995, 73, 347; Elices, Cell Adhesion in Human Disease, Wiley, Chichester 1995, p. 79; Kuijpers, Springer Semin. Immunopathol. 1995, 16, 379.
On account of the role of the VCAM-1/VLA4 mechanism in cell adhesion processes, which are of importance, for example, in infections, inflammations or atherosclerosis, it has been attempted by means of interventions into these adhesion processes to control illnesses, in particular, for example, inflammations (Osborn et al., Cell 1989, 59,1203). A method of doing this is the use of monoclonal antibodies which are directed against VLA4. Monoclonal antibodies (mAB), of this type, which as VLA-4 antagonists block the interaction between VCAM-1 and VLA4, are known. Thus, for example, the anti-VLA4 mAB HP2/1 and HP1/3 inhibit the adhesion of VLA-4-expressing Ramos cells (B-cell-like cells) to human umbilical cord endothelial cells and to VCAM-1-transfected COS cells. The anti-VCAM-1 mAB 4B9 likewise inhibits the adhesion of Ramos cells, Jurkat cells (T-cell-like cells) and HL60 cells (granulocyte-like cells) to COS cells transfected with genetic constructs which cause VCAM-6D and VCAM-7D to be expressed. In vitro data with antibodies which are directed against the .alpha.4 subunit of VLA-4 show that the adhesion of lymphocytes to synovial endothelial cells is blocked, an adhesion which plays a part in rheumatoid arthritis (van Dinther-Janssen et al., J. Immunol. 1991,147, 4207).
In vivo experiments have shown that an experimental autoimmune encephalomyelitis can be inhibited by anti-.alpha.4 mAB. The migration of leucocytes into an inflammatory focus is likewise blocked by a monoclonal antibody against the .alpha.4 chain of VLA4. The influencing of the VLA4-dependent adhesion mechanism by antibodies was also investigated in an asthma model in order to investigate the role of VLA4 in the recruitment of leucocytes into inflamed lung tissue (U.S. Pat. Ser. No. 07/821,768; EP-A-626 861). The administration of anti-VLA-4 antibodies inhibited the late-phase reaction and airway overreaction in allergic sheep.
The VLA-4-dependent cell adhesion mechanism was also investigated in a primate model of inflammatory bowel disease (IBD). In this model, which corresponds to ulcerative colitis in man, the administration of anti-VLA4 antibodies resulted in a significant reduction in the acute inflammation.
Moreover, it was possible to show that VLA4-dependent cell adhesion plays a part in the following clinical conditions including the following chronic inflammatory processes: rheumatoid arthritis (Cronstein and Weismann, Arthritis Rheum. 1993, 36,147; Elices et al., J. Clin. Invest. 1994, 93, 405), diabetes mellitus (Yang et al., Proc. Natl. Acad. Sci. USA 1993, 90, 10494), systemic lupus erythematosus (Takeuchi et al., J. Clin. Invest. 1993, 92, 3008), allergies of the delayed type (type IV allergy) (Elices et al., Clin. Exp. Rheumatol. 1993, 11, S77), multiple sclerosis (Yednock et al., Nature 1992, 356, 63), malaria (Ockenhouse et al., J. Exp. Med. 1992,176,1183), arteriosclerosis (O'Brien et al., J. Clin. Invest. 1993, 92, 945), transplantation (Isobe et al., Transplantation Proceedings 1994, 26, 867-868), various malignancies, for example melanoma (Renkonen et al., Am. J. Pathol. 1992, 140, 763), lymphoma (Freedman et al., Blood 1992, 79, 206) and others (Albelda et al., J. Cell Biol. 1991,114, 1059).
VLA-4 blocking by suitable antagonists accordingly offers effective therapeutic possibilities, in particular, for example, of treating various inflammatory conditions including asthma and IBD. The particular relevance of VLA-4 antagonists for the treatment of rheumatoid arthritis in this case results, as already stated, from the fact that leucocytes from the blood must first adhere to endothelial cells before they can migrate into the synovium, and that the VLA4 receptor plays a part in this adhesion. The fact that VCAM-1 is induced by inflammatory agents on endothelial cells (Osborn, Cell 1990, 62, 3; Stoolman, Cell 1989, 56, 907), and the recruitment of various leucocytes into areas of infection and inflammatory foci has already been discussed above. In this respect, T cells adhere to activated endothelium mainly via the LFA-1/ICAM-1 and VLA-4/VCAM-1 adhesion mechanisms (Springer, Cell 1994, 76, 301). On most synovial T cells, the binding capacity of VLA-4 for VCAM-1 is increased in rheumatoid arthritis (Postigo et al., J. Clin. Invest. 1992, 89, 1445). Additionally, an increased adhesion of synovial T cells to fibronectin has been observed (Laffon et al., J. Clin. Invest. 1991, 88, 546; Morales-Ducret et al., J. Immunol. 1992, 149,1424). VLA-4 is upregulated both in the course of its expression and with respect to its function on T lymphocytes of the rheumatoid synovial membrane. The blocking of the binding of VLA-4 to its physiological ligands VCAM-1 and fibronectin makes possible an effective prevention or alleviation of articular inflammatory processes. This is also confirmed by experiments with the antibody HP2/1 on Lewis rats with adjuvant arthritis, in which an effective prevention of illness has been observed (Barbadillo et al., Springer Semin. Immunopathol. 1995, 16, 427). VLA-4 is thus an important therapeutic target molecule.
The abovementioned VLA-4 antibodies and the use of antibodies as VLA4 antagonists are described in the Patent Applications WO-A-93/13798, WO-A-93/15764, WO-A-94/16094, WO-A-94/17828 and WO-A-95/19790. In the Patent Applications WO-A-94/15958, WO-A-95/15973, WO-A-96/00581, WO-A-96/06108 and WO-A-96/20216, peptide compounds are described as VLA4 antagonists. The use of antibodies and peptide compounds as pharmaceuticals, however, is afflicted with disadvantages, for example lack of oral availability, rapid degradation or immunogenicity on longer-term use. There is thus a need for VLA4 antagonists having a favorable profile of properties for use in therapy and prophylaxis.
WO-A-94/21607 and WO-A-95/14008 describe substituted 5-membered ring heterocycles, EP-A-449 079, EP-A-530 505 (U.S. Pat. No. 5,389,614), WO-A-93/18057, EP-A-566 919 (U.S. Pat. No. 5,397,796), EP-A-580 008 (U.S. Pat. No. 5,424,293) and EP-A-584 694 (U.S. Pat. No. 5,554,594) describe hydantoin derivatives which have platelet aggregation-inhibitory actions. EP-A-842 943 (German Patent Application 19647380.2) describes that compounds of this type surprisingly also inhibit leucocyte adhesion and are VLA4 antagonists. Further investigations showed that the compounds of the present invention are also strong inhibitors of leucocyte adhesion and VLA4 antagonists.